Welding Part I

It's been a long time since my last post; busy at work and many other projects going on. Here's a quick update to describe the great progress made on the welds!

Lower longeron external sleeves and gear bolt bushings were welded in place as well as the rudder pedal hinge bushings:

I took this opportunity to shift my pedals 5/16'' forward since I'm 6'1'' tall and my knees were a little close to my instrument panel with my previous setup.

Next step is to weld the brake cylinder attachment tubes and bushings as well as the lateral diagonals. Last step will be to weld the footrest brackets and lateral panel nutplate lugs.

I take the opportunity the congratulate my acro mates Luc Martineau (Sportsman, Pitts S-2C) and François Marquis (Intermediate, Christen Eagle) who got to the Wildwood Acroblast contest this week-end and both won first place of their category! Great job guys!! Here's a little picture of us 3 almost 2 years ago:

First pieces tack welded

Quick update to mention that the lower longerons were tack welded in place yesterday! The forward gear bolt bushing alignment was also checked to ensure that the gear was going to be at the desired location:

Square channels were used as a guide to check the gear alignment:

Mark is also going to weld a reinforcement plate for my wobble pump attachment bracket that was cracked. I took the opportunity to drill nutplate holes to ease up the installation:

Next step is the final welding of the lower longeron reinforcement sleeves. Stay tuned!

Preparing the sleeves

This week, progress was made on the preparation for the bottom longeron reinforcement. The longeron section that was removed was replaced with new sections and welded in place. Also, the external sleeves were cut and trimmed to fit the shape of the adjacent tubes:

As you can see on the picture above, the forward gear attachment bushings were slid in place to check the fit. They will be welded a little longer and then will be trimmed using a counterbore tool such as this one:

In the meantime, I worked on my nosebowl attachment. My nosebowl is a two piece type such that you don't have to remove the prop to remove the cowl. When I bought the airplane, the two halfs were riveted together at the center which was kinda dumb. I decided to install piano hinges last year to make them splittable again:

However as you can see, there was some chafing with the flywheel and one side was getting close to failure. I realized this the morning I was leaving for my last contest of the year last year. I had to cut and fix a plate (therefore the two holes on the outboard edge) as a last minute fix and managed to leave on time for the contest. While the fuse is getting fixed, I took the time to work on a new attachment design (inspired on Wes Liu's S2-A I saw at the contest in question). An aluminium plate riveted on one side and nutplated on the other side.

First I determined the best nutplate location, cut the aluminium brackets, bent them and drilled them. Here is a shot with both plates clecoed in place:

Then I made alumiprep and alodyne treatments to protect them from corrosion (thanks to my friend Scott for the chemicals):

And finally riveted them in place:

The nutplates are riveted on the foward side of the top piece. The holes beside the bolt hole on the bracket above will serve as rivet head clearance holes. I will upload pictures of the final nosebowl once it's back from the paint shop.

The plan for this week is to weld the bottom longerons sleeves in place as well as the gear bushings. These will be a challenge to fix since they need to be aligned such that the gear beam is perpendicular to the fuselage axis.

The repair is progressing step by step. Thanks all again for you encourangements, it really helps keeping the morale up, especially for days like today with wonderful wx!!

Reach out and build something

Last week I received the 4130 steel tubes and plates required for the repair : ) I also took the opportunity to order new ignition cables (as recommended by my friend and Pitts mentor, François) as well as plenty of AN hardware to replace the old one:





The 1" OD X 0.120" wall tube that is going to serve as a sleeve over the bottom longerons per Steen plans is impressively massive:

I brought all this to the welding shop last week-end. My welder Mark did a great job of removing all the crap from the bad repair with minimal intrusion to the tubes to be preserved. In the process, he discovered that the lower longerons already had internal sleeves in good shape, and securely welded! This is good news since it's going to provide better stiffness continuity all the way up to the forward end of the longerons. However, the sections of each lower longerons where the side diagonals were welded were in such a bad condition that we chose to saw them off:

These will be replaced with sections of 3/4" OD X 0.035" tube (same as the longeron) over which the 1" external sleeve will be welded later on.

Next step is to perform a dye-penetrant inspection on many locations of the foward fuse to ensure we are aware of all the cracks to be repaired before welding the new tubes in place. The items I intend to focus on during this inspection are:

1. Lower longerons (in case there is more than the 2 cracks I found)
2. Fuel tank attachment bushings
3. Lower wing attachment bushings
4. Flying wire attachment lugs

While the clean up process was being finished at the welding shop, I made some work on my nosebowl at the hangar. I intend to dedicate a post on this shortly. Stay Tuned!

Last steps of dismantling

Over the last week, Mark made great progress in removing the excess welding maetrial from the old repair. He pretty much removed everything that needed to be removed except the portion of the flat plates still welded to the bottom longerons.

 

I wanted to use these plates one last time before removing them and here is why. As I need to oversize the gear attachment bolts (AN5 to AN6 size), I need to get rid of the old bushings and replace them with larger ones. I decided to progressively drill them out until reaching the OD of the new bushings. In order to achieve that with reasonable precision, we decided to fix a mag drill on a steel beam sitting on the bottom longerons while the fuse was mounted upside down:

 

As you can see, having the old flat plates still welded to the longerons was a good reference to clamp the steel beam on the fuse. Big thanks to friendly Claude from whom I could borrow the mag drill.

 

While Mark was working on removing the old welding last week, I decided to take the opportunity to make a small modification to my landing gear. I wanted to do this for a long time and since everything is teared down, it is much easier to do it now: rotate my brake calipers aft. My original setup was with the calipers mounted downwards and I didn't like much the idea of scraping the caliper on the ground if I ever have a flat tire or tire burst.

After a few tests playing with the different components, I found the caliper position that I think was a good compromise; it needed a small adjustment of the nutplate attachment lug and a bit of trimming on my wheelpants.

First I washed the wheel hub and brake parts with varsol to have clean parts to work with:

 

Then, I slightly trimmed the nutplate lug, and with the use of a cardboard template and my Dremel with a cutting wheel, I trimmed of the piece needed on the wheelpant:

And here is the almost-final result:

 

I'm going to have a little extra trimming to do to clear the fitting on the top, but I preferred to have the final fitting in hand before doing that.

The 4130 steel tubes and plates are in transit right now. With chance, I will receive it this week and start trimming the first tubes this week-end!